Earth boring tools



May 6, 1958 q 0. K. OLSEN EARTH sonmc; TOOLS Filed Sept. 25, 1954 INVENTOR. 0/6 A. Olsen fifl a ATTQRNEY Fig. 3

2,833,521 Patented May 6, 1958 EARTH BORING TOOLS Ole K. Olsen, Garland, Tex. Application September 23, 1954, Serial No. 457,973 6 Claims. (Cl. 255-302) This invention relates to earth boring tools and more particularly to drill bits used in the boring of shotholes, and is in part a continuation of my co-pending application, Serial No. 394,060, filed November 24, 1953, and now abondoned.

An object of the invention improved drilling bit.

Another object is to provide a drill bit having a plurality of outer roller cutters and a plurality of drag bits or blades disposed centrally between and in advance of the rotatable cutters.

A further object of the invention is to provide a drill bit, of the type described, wherein the roller cutters and drag blades are secured to a body having a large bore which permits voluminous circulation of drilling fluids downwardly through the body and past the roller cutters and drag bits.

Another object is to provide a drill bit, of the type described, which is of strong construction and which may be easily assembled, and which may be quickly and simply disassembled for repair or replacement of parts, and as readily reassembled.

A furtherobject is to provide a drill bit, of the type described, wherein the hubs on which the roller cutters are mounted are rigidly held in position by the drag blades, the connection between the drag blades and vthe hubs for the rollers being severable to permit removal and disassembly of both the drag blades and the roller cutters and their associated parts.

A still further object of the invention is to provide a drill bit, of the type described, wherein the drag blades penetrate earth formations to form the central portion of the hole being drilled and the roller cutters enlarge and size the hole for-med by the drag blades, the drag blades serving as guides for the roller cutters.

Additional objects and advantages of the invention will readily be apparent from the reading of the following description of devices constructed in accordance with the invention, and reference to the accompanying drawings thereof, wherein:

Figure 1 is a perspective view of a preferred embodiment of the new and improved drill bit;

Figure 2 is an enlarged side view, partly in elevation and partly in section, of the drill bit illustrated in Figure 1;

Figure 3 is a plan view of the drill bit as seen from the bottom of Figure 2; and

Figure 4 is a fragmentary sectional view of a modified form of roller cutter mounting.

Referring now to the drawings, the numeral indizates a drill bit having a main body or shank 11 pro- Iided with the usual screw threads 12 on its upper portion or attaching the drill bit to a string of drill pipe by neans of which the drill bit is rotatable in any suitable nanner. The body is provided with a central bore 13 hrough which drilling fluid may be passed downwardly rom the drill pipe string to the earth formation being lrilled.

The body 11 is enlarged at its lower end to provide is to provide a new and a plurality of uniformly circumferentially spaced hub supporting arms 15. While the supporting arms are preferably integral with the main body, they may be separately formed and secured to the body in any suitable manner, as by welding, if desired.-

The lower portion of the bore of the body is enlarged and the inner surfaces 17 of the supporting arms extend downwardly and outwardly, and each arm has a hub receiving bore 18 formed in its inner surface.

An annular boss or spacer ring 19 is formed on each supporting arm surrounding the bores 18, and these bosses engage the inner ball bearing race 20 disposed about each of the hubs 21 which engage in the bores 18 and have roller cutters 22 mounted thereon. The hubs 21 extend through central openings 23 of the roller cutters and are provided at their inner ends with enlarged heads or flanges 24 for retaining the roller cutters in place thereon.

The roller cutters are also provided with opposed annular recesses 25 concentric with the central opening 23, and the ball bearing race 20 is received in the outer annular recess while the hub flange 24 extends into the opposite or inner annular recess. Ball bearings 27 are interposed between the roller cutter and the ball bearing race, and between roller cutter in suitable grooves forming races therein, so that the roller cutters may rotate freely about the hubs.

The hubs are held in assembly 28 having a plurality of angularly disposed drag blades 29 formed at their edges with beveled or inclined abutment surfaces 31 which abut the inner end of the head 24 of the adjacent hub 21 and hold the outer end of the hub in engagement in the bore 15 in the arms of the body. The inclined abutment surfaces 31 of the drag blades are welded to the heads of the hubs against which they formed.

Each of the drag blades has a plurality of steps 33- formed thereon, disposed beneath and inwardly of the roller cutters 22. The uppermost steps 33a have lateral extensions 34 which extend outwarly beyond the inner edges of the hub flanges 24 to points adjacent the cutting teeth 35 of the roller cutters so that a full cutting-of allmaterial in the bore of the hole being drilled is obtained by the joint action of the drag blades and roller cutters. Each of the drag blades is provided with inserts 36 of a very hard wear resistant substance, such as tungsten inserts may be rigidly secured in appropriately shaped recesses formed in the blades, in any suitable manner, as by welding, brazing, or the like.

In use, the drill bit 10 is secured to the lower end of a string of drill pipe, which is rotated at the surface in the usual manner. The lowermost and innermost steps 33 of the drag blades form a point or guide, and are the first to engage and penetrate the earth formations as the drill bit is rotated, the next outer steps prothe earth formations so that the drag The hardened ingressively engaging blades initially form the bore hole.

serts 36, of course, face in the direction of rotation of the blades and blades.

provide the cutting edges of the drag The drag blades are retained in the bore they form,"

and thus also serve as a guide for the roller cutters which cut the larger area of the outer portion of the bore hole duringthe drilling operation. larger cross sectional area or hole than do the drag blades, and they also size and shape the wall of the hole as the drill bit penetrates the earth formations. greater part of the work of drilling the hole is done by the roller cutters, while the drag blades cut rapidly in the hub flange 24 and theplace by a drag bitor blade abut, whereby a rigid structure is.

carbide, a special alloy steel, or the like. The- The roller cutters cut a' Thus, the' the. center portion of the hole and serve as a guide for the roller cutters. Drilling fluid may be pumped downwardly through the bore 13 of the main body 11 of the bit and outwardly through the spaces between the drag blades to the hole being drilled. The drilling fiuid may then flow upwardly through vertical flow courses or longitudinal grooves 37 formed on the exterior of the body between the hub supporting arms 15.

Among the chief advantages of this drill bit are its simplicity, strength and ease of construction. It will be evident that the bit can be easily assembled by inserting the hubs through the central apertures 23 of the roller cutters and the ball bearing races after the ball bearings 27 have been placed in proper positions. The outer ends of the hubs are then inserted in the bores 13 in the supporting arms 15. The drag blade assembly 28 is then inserted between the hubs so that the inclined abutment surfaces 31 of the drag blades engage the inner surfaces of the heads 24 of the'hubs. A simple welding operation then rigidly secures the drag blades to the hubs so that the hubs are firmly and positively secured in position on the supporting arms 15, and the drill bit is ready for use.

Furthermore, the bit may be readily repaired or parts replaced simply by cutting the welds holding the drag blades to the heads of the hubs, whereuponboth the roller cutters and the drag blades may be repaired or replaced, as desired ornecessary. After such repair or replacement of parts, the bit is reassembled by welding the drag blades to the heads of the hubs in the manner just described.

It will thus be seen that a new and improved drill bit has been provided which has a main body 11, having a plurality of circumferentially spaced supporting arms provided with inner hub receiving bores 18. It will also be seen that the hubs 21 rotatably support roller cutters 22, the hubs being positively rigidly held in place by a drag blade assembly 28, disposed centrally between the hubs and rigidly secured to the inner ends of such hubs. It will also be seen that the drag a plurality of drag blades 29 which extend angularly outwardly from a common longitudinal axis to the hubs, and which have stepped cutting edges disposed inwardly of and below the cutting teeth 35 of the roller cutters, such roller cutters extending outwardly of the supporting arms as best seen in Figures 2 and 3. It will also be apparent that the drag blades penetrate earth formations to form a hole or bore and act as a guide for the roller cutters which then cut the larger cross-sectional area of the bore hole and shape and size the hole.

A modified form of mounting for the roller cutters is shown in Figure 4, wherein the hub supporting arms 45 are each formed with a hub receiving bore 48 in its inner surface 47 and with anannular counterbore 49 surrounding the hub receiving base.

Roller cutters 42 each have a central hub bore 43 and a pair of opposed annular recesses or counterbores 44- concentric with said central bore, and a hub 51 having at its inner end an enlarged head or flange 52 which extends through the central bore of the cutter and has its head flange positioned in the inner counterbore 44 for retaining the cutter on the hub. The hub 51 extends through the cutter and through a bearing race 53 into the hub receiving bore 48 in one of the arms 45. The inner portion of the bearing race 53 is received in the outer counterbore 44 of the roller cutter, and the outer portion of said race is fitted tightly in the annular counterbore 49 in the supporting arm 45 of the bit body. Ball bearings 55 are interposed between the roller cutter and the bearing race 53, and between the hub head flange 52 and the roller cutter, in suitable grooves forming races therein, so that the roller cutters may rotate freely about the hubs.

The bearing race 53 is secured in place on the hub 51 by means of a weld 52, the cutter 42, the bearings 55 and the bearing race 53 are all held in properly assembled position and may be blade assembly includes 60, whereby the hub, its head flange handled as a unit in assembling and constructing the bit. An annular beveled recess 65 between the counterbore 49 and the hub receiving bore 48 provides clearance for the weld 69, whereby the bearing race 53 may seat firmly in the counterbore 49 and the hub fit properly in the bore 48. The hubs are held in place by the drag blade assembly 28 in the same manner as the hubs of the form first described.

This modified form of roller cutter mounting provides a more rigid mounting and support for the bearing race, whereby the hub 51 is held more rigidly and securely against thrusts and torques resulting from the use of the bit in drilling. Also, the bearing and cutter assembly may be more easily manipulated in the assembling of the bit, during manufacture or repair. Otherwise, there is no difference in the structure or function of the several forms of the bit.

It will particularly be noted that the drag blade and roller cutter assembly is readily, simply andeconomically assembled and secured in place onthe body by welding the drag blades to the inner ends of the hubs, and that the assembly may be quickly and easily disassembled by cutting away such welds. This provides for quick economical repair or replacement or" parts of the bit.

The foregoing description of the invention is explanatory only, and changes in the details of the method described and of the construction illustrated may be made by those skilled in the art, within the scope of the appended claims, without departing from the spirit of the invention.

What I claim and desireto secure by Letters Patent is:

1. A drill bit including: a body having downwardly and outwardly extending circumferentially spaced supporting arms; at least three roller cutters disposed between said arms; means for rotatably mounting said roller cutters on said arms; and a drag blade assembly disposed between said 'roller cutters and secured solely to said mounting means to lock said mounting means to said supporting arms; said drag blade assembly including radially extending blades corresponding in number to the roller cutters and each connected at its upper end to the mounting means for one of said roller cutters, said blades each having cutting edges disposed inwardly of and below said roller cutters whereby said drag blades first penetrate earth formations to form a hole which is subsequently enlarged and shaped by said roller cutters; said drag blades each having a plurality of steps formed thereon disposed in progressively upward and outward relation from a central lowermost point portion.

2. A drill bit including: a body provided with a central longitudinal bore; at least three circumferentially spaced arms depending from said body, each of said arms having an inner surface provided with a downwardly and inwardly extending hub bore; a plurality of hub members disposed inwardly of said arms, each hub member having its outer end portion slidably engaged in the hub bore of one of the supporting arms; a roller cutter member rotatably mounted on each hub member inwardly of the associated arm; and a drag blade assembly having radially extending blades corresponding in number to the roller cutter members, said blades having outer abutment portions engaging the inner ends of said hub members and welded thereto to provide the sole connection between said blades and said body and the sole support for said blades, said blades when so connected providing the sole means retaining said hub members in said hub bores of the supporting arms.

, 3. A drill bit including: a body having a longitudinal bore; a plurality of circumferentially spaced supporting arms depending from said body and each having an inner surface provided with a downwardly and inwardly extending hub bore; a plurality of hub members each having its upper outer end slidably removably engaged in the hub bore of one of the supporting arms and having an enlarged head at its lower inner end; a roller cutter mounted on each hub member and confined thereon between the associated supporting arm and the head of its hub member; and a plurality of drag blades corresponding in number with the hub members, said lades being centrally united and each extending radially outwardly and having an abutment surface engaging the head of a hub member to hold the outer end of said hub member engaged in the hub bore of its associated supporting arm; means rigidly securing the abutment surfaces of the drag blades to the heads of the hub members to lock the hub members in place in said hub bores of the supporting arms to provide a rigid cutting assembly, said last-named means providing the sole connection between the body of the bit and the drag blades, said blades when so connected providing the sole means holding the hub members in their respective bores.

4. A drill bit of the character set forth in claim 3 wherein the drag blades each have a plurality of steps formed thereon disposed progressively inwardly and downwardly from adjacent its associated roller cutter to a central lowermost point portion, whereby the drag blades first cut a hole and the roller cutters subsequently enlarge and shape the hole.

5. A drill bit including: a body having a longitudinal bore; a plurality of circumferentially spaced supporting arms depending from said body and each having an inner surface provided with a downwardly and inwardly extending hub bore and a bearing supporting surface surrounding the lower inner end of said bore; a plurality of hub members each having its upper outer end slidably engaged in the hub bore of one of the supporting arms and having an enlarged head at its lower inner end; a roller cutter mounted on each hub member and confined thereon between the bearing supporting surface of its associated supporting arm and the head of its hub member; and a plurality of drag blades, corresponding in number with the hub members, said blades being centrally united and each extending radially outwardly and having an abutment surface engaging the head of a hub member to hold the outer end of said hub member engaged in the hub bore of its associated supporting arm; means rigidly securing the abutment surfaces of the drag hub members to lock the hub members in place in said hub bores of the supporting arms to provide a rigid cutting assembly, said means securing the drag blades to the heads of the hub members providing the only connections between the drag blades and the body, said blades when so secured providing the sole means holding the hub members in their respective bores.

6. A drill bit including: a body having a longitudinal bore; a plurality of circumferentially spaced supporting arms depending from said body and each having an inner surface provided with a downwardly and inwardly extending hu-b bore, each of said inner surfaces also having a counterbore surrounding said hub bore; a plurality of hub members each having its upper outer end engaged in the hub bore of one of the supporting arms and having an enlarged head at its lower inner end; a roller cutter mounted on each hub member and confined thereon between the associated supporting arm and the head of its hub member; a bearing race secured on each hub member and disposed in the counterbore in the inner surface of the supporting arm; and a plurality of drag blades corresponding in number with the hub members, said blades being centrally united and each extending radially outwardly and having an abutment surface engaging the head of a hub member to hold the outer end of said hub member engaged in the hub bore of its associated supporting arm; means rigidly securing the abutment surfaces of the drag blades to the heads of the hub members to lock the hub members in place in said hub bores of the supporting arms to provide a rigid cutting assembly.

blades to the heads of the References Cited in the file of this patent UNITED STATES PATENTS 

